Technical Field
The present disclosure generally relates to electronic devices and circuits and, more specifically, to NFC (Near Field Communication) devices.
Discussion of the Related Art
More and more portable communication devices (for example, cell phones) are equipped with NFC-type near field communication systems. The principle is to have a same device capable of operating either as an electromagnetic transponder or an electronic tag (card mode) communicating with another mobile device or with a terminal emitting a high-frequency electromagnetic field, or as an electromagnetic transponder reader (reader mode) generating a field capable of being detected by other devices configured in card mode or by other types of transponders.
A same device however has to select the card or reader mode in which it operates. In practice, the device has a card mode default configuration and is only placed in reader mode under the effect of a control signal triggered by one of the applications of the device.
To avoid having two devices located close to each other simultaneously start operating in reader mode, which would adversely affect any communication, anticollision mechanisms are provided. However, such mechanisms do not avoid all collisions, in particular, when an NFC device is in the field of a read/write terminal, called previous-generation terminal, which does not comply with the NFC Forum and ISO 18092 standards, and only complies with ISO standard 14443.